Homemade yogurt is always thinner than store bought. I have made goat milk yogurt for over 30 years and written a couple of cheesemaking books. In particular my first book (Goats Produce Too!) addresses the problem of thinner yogurt and how to compensate for this. Most people expect their yogurt to have the consistency and texture of store bought yogurt. That is achieved by adding stabilizers, gelatins and non fat milk solids. Read those store bought cartons and you will see something like that listed. The exception of course is greek yogurt which is thicker because they have drained it. The thickness of the yogurt would naturally be thicker with Jersey milk as the buttermilk (milk solids) content is much thicker. Non fat milk solids is simply powdered milk. We rarely ate our yogurt plain so I developed recipes that made flavored turn out thick like the store bought stuff. So the fact that it was thin when it was cultured was not a concern when I was turning it into a flavored product. Vanilla and coffee flavored yogurt I would add powdered milk to before culturing and it would turn out thick and great tasting from the get go. I hope this helps you to understand that without some addition you simply cannot get the results you are looking for. But you can make great tasting thick yogurt with some good recipes.